FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
AND
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
TITLE OF THE INVENTION
"PROCESS FOR TREATMENT OF FLUE GAS"
APPLICANT
Tata Consulting Engineers Limited of Matulya Centre, A-249, Senapati Bapat Marg, Lower Parel (West), Mumbai 400 013, Maharashtra, India; Indian
The following specification particularly describes the invention and the manner in which it is to be performed

Field of invention: The present invention relates to a process of wet removal of an environmental contaminant from flue gas generated by burning of combustants by absorption in sea water which is then cooled and treated so that sea water may be returned without damage to the marine environment. In particular, the present invention relates to a process in which at least a part of treated sea water is recirculated eliminating the need for withdraw surplus sea water.
Background and prior art: Energy conversion today is based largely on burning of fossil fuel. The presence of environmental contaminants in the smokes discharged from burning of combustants such as heavy oil, coal, and such power plants and other combustion facilities is a serious environmental concern. Generally, the environmental pollutants include a combination of SOx, NOx, CO2, particulate matter and polycyclic aromatic hydrocarbon. Such oxides travel with the exhaust gases from source to regions leading to acid rain, acid fog, polluting the sea, air and soil over vast regions having detrimental effects on human health.
In the regulation of environmental pollution, strenuous studies are being carried out and accessory purification facilities are being constructed at huge expenditures, by electric power companies and chemical companies. There are various commercial and well established techniques for removal of undesired acidic components. In particular, for removal of Sulphur dioxide flue gas desulfurization takes place in a complex, large-scale chemical reactor which is located between the combustion chamber and the smoke stack. Usually, the combustion products (flue gases) are exposed to a lime or limestone slurry that is sprayed in their path. Sulfur dioxide in the gas reacts with the spray and goes into solution, from which it is later removed, dewatered and extruded in the form of sludge. Flue Gas Desulphurisation processes can be categorized by process i.e. use of catalysts such as dry, lime, limestone, dual alkali, sodium carbonate, etc and without use of catalysts such as sea water.

As an example of the former category, US 4,804,523 discloses process of desulphurization in which the flue gas is contacted with recirculating absorbent stream in a scrubber. The absorbent is formed by combining sea water and hydrated lime at pH in the range of 8.0 to 10.0 producing magnesium hydroxide by reaction of hydrated lime with magnesium present in sea water. The absorbent is added to recirculating absorbent stream which is contacted with flue gas. In contact vessel, magnesium reacts with SO2 to form magnesium sulphite and bisulfate which are oxidized to soluble magnesium sulphate by air sparging in contact vessel or separate tank. Magnesium sulfate reacts with hydrated lime to regenerate magnesium hydroxide which recirculates as slurry in scrubber. However, this prior art technology suffers from the disadvantage of having a tendency toward chemical scaling, plugging and erosion which can frequently halt its operation.
Another technique for removal of environmental contaminant from flue gas is by simply using sea water without the help of any additional chemicals. The use of sea water for flue gas purification has been previously proposed. In most cases the neutral alkalinity of sea water is relied upon to desulfurize the combustion effluent single pass system. Typically in this technique as depicted in figure 1, sea water is independently drawn from the sea and used for SO2 removal in flue gas desulphurization system. Hence total sea water drawn is equal to sum total of sea water drawn for cooling tower make up (107) and sea water drawn for flue gas desulphurization plant (106) as shown in figure 1. The flue gas desulphurization scrubber outlet hot water (117) is led to a dilution cum aeration tank (110) by gravity. This quality of water cannot be led to sea directly as it affects aquatic/marine life. Hence dilution water drawn from the sea by means of dilution pump (109) is pumped to the dilution cum aeration tank (110). Thereafter air is bubbled through the water by aeration means (104). This aeration process helps in oxygenation to convert SO2 formed in flue gas desulphurization scrubber to SO4 and also to remove CO2 formed which in turn helps in increasing the pH level of the flue gas desulphurization scrubber outlet water. Treated water (103) is then led to sea. Separate sea water intake pumps (102) are provided for pumping water for

cooling tower make up (105). Cooling tower blow down water (118) is suitably treated before disposing to sea separately if required to meet the environmental regulations. Treatment is generally to elevate pH if necessary by the same dilution water. However abundant precaution is taken before discharge of water to sea.
However, in this technique, total amount of water required by flue gas desulfurization scrubber and by cooling towers has to be withdrawn from the sea. Although effective, use of sea water alone requires very large flow to remove a high percentage of sulfur dioxide. The equipment and operating costs for handling such large volumes of water can be prohibitively expensive. Moreover, the sea water used to absorb sulfur dioxide will also absorb large amounts of heat, which results in a temperature rise which can be determined in a marine environment. Neutralization and oxidation of the scrubber effluent will require additional treatment capability, further increasing the capital and operating costs of the process.
It is thus desirable to provide processes which employ sea water efficiently scrubbing sulfur dioxide gases. In particular, such methods and systems' should be able to function with relatively low amounts of sea water limiting the need for withdrawing large amounts of water from the sea. It is further desirable if aqueous effluent from such a treatment process could be returned to the marine environment without further treatment and that the process would not require separation of solid wastes at any point. Finally it is highly desirable if the process results in only a limited temperature rise in the sea water being returned to the marine environment.
Summary of the invention: The present invention provides a process for treating flue gas comprising an environmental contaminant by using sea water by absorption in sea water which is then treated so that sea water may be returned to the recipient without damage to the aquatic environment. In particular, at least a

part of withdrawn sea water is recirculated to eliminating the need to withdrawn surplus amounts of sea water. More particularly, this invention relates to SO2 removal in a power plant using sea water for condenser cooling in open re-circulating type cooling system involving cooling towers.
Brief Description of the Drawings: A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:
Figure 1 illustrates flue gas desulphurization plant depicting conventional method for removal of sulphur dioxide by flue gas desulphurization.
Figure 2 shows the process flow chart for method as per embodiment 1 in which makeup sea water drawn from the sea is used by cooling tower (205) followed by the scrubber (201), said makeup water is partly re-circulated within the apparatus (200) before being disposed to the sea.
Figure 3 illustrates the process flow chart for method as per embodiment 2 in which makeup sea water drawn from the sea is used by flue gas scrubber (301) followed by cooling tower (305), said makeup water is fully re-circulated within the apparatus (300) before being disposed to the sea.
Figure 4 illustrates the process flow chart for method as per embodiment 3 in which makeup sea water drawn from the sea is used by flue gas scrubber (401) followed by cooling tower (405), said makeup water is fully re-circulated within the apparatus (400) before being disposed to the sea.
Figure 5 shows the process flow chart for method as per embodiment 4 in which makeup sea water drawn from the sea is used by cooling tower (505)

followed by the scrubber (501), said makeup water is partly re-circulated within the apparatus (500) before being disposed to the sea.
Detailed Description: In the following detailed description, reference numerals are used to identify structural elements, portions of elements, surfaces and areas in the drawings. It should be understood that like reference numerals are intended to identify same structural elements, portions, or surfaces consistently throughout the several drawing figures, as such elements, portions or surfaces may be further described or explained by the entire written specification. As used in the following description, the terms 'horizontal \ 'vertical', 'left', 'right', 'up', 'down' as well as adjectival and adverbial derivatives thereof (e.g. 'horizontally', 'rightwardly', 'upwardly' etc) refer to the relative orientation of the illustrated structures as the particular drawing figure faces the reader. Similarly, the terms like 'inwardly' and 'outwardly' refer to the orientation of a surface of revolution relative to its axis.
The present invention provides for a process for treating flue gas by using sea water which flue gas being generated from burning of combustants and comprising at least one environmental contaminant, in an apparatus (200,300,400,500). The environmental contaminant comprised in the flue gas is usually combination of SOx, NOx, CO2, particulate matter, polycyclic aromatic hydrocarbon. The detailed description provided hereinbelow relates to processes for treating flue gas where environmental contaminant is SOx, particularly SO2 and said process is flue gas desulphurization explaining the present invention i.e. process of recirculation of makeup sea water. It is to be understood that this description does not limit the scope of this invention in any manner and that the present invention pertaining to process of recirculation of sea water. In accordance with the present invention, this detailed description combined with appending figures 2-5 illustrate an open recirculating type flue gas desulphurization plant in accordance with principles of present invention.

In coastal power plants it is advantageous to use open re-circulation system with wet cooling tower for condenser cooling, for withdrawing sea water in flue gas desulphurization plant to remove SO2 from flue gas and let out to sea after treatment. In the present invention, the makeup sea water is at least partly recirculated and reused eliminating the need to withdraw surplus amounts of sea water. Accordingly, the present invention provides for embodiments wherein the withdrawn sea water is at least partly re-circulated within apparatus (200,500) or fully re-circulated within the apparatus (300, 400). The benefit of the present invention is in reduction of water drawn from the sea compared to known conventional system illustrated in appended figure 1.
In general, the process of the present invention comprises contacting, in a scrubber, (201,301,401,501), said flue gas with sea water resulting in absorption of the environmental contaminant therewithin leading to acidification of the sea water. During absorption reaction, flue gas comprising SO2 and water from the liquid dissolves into sulfite and hydrogen ions, resulting in final absorption at a pH of around 3.
S02(Gas) ↔ S02 (Liquid)
SO2 + H2O ↔ HSO3- + H+
HSO3- ↔ S032- + H+
The transferred acidic sea water comprising absorbed environmental contaminant is sent to neutralization zone (230, 330, 430, 530). Neutralisation zone comprises of at least one of dilution chamber, aeration means, means for addition of pH raising agent and ash settling pond. In the neutralization zone (230, 330,430, 530), said acidic sea water is neutralized by at least one mechanism selected from addition of pH raising agent or aeration or dilution with makeup sea water thereby reacting said absorbed environmental contaminant with bicarbonate ions (HCO'3) present in used sea water to carbon dioxide and water rendering the blowdown

water environmentally safe for returning to the sea. During neutralizing reaction, bicarbonate ions in sea water react with hydrogen to increase the pH.
HCO-3 + H+ ↔ CO2 + H2O
This is followed by the step of disposing at least a part of blowdown sea water into the sea.
The alkalinity of sea water is primarily influenced by bicarbonates and carbonates of calcium and magnesium. The pH of sea water is usually around 7.5-8.5. It can be neutralized with SO2 during a reaction. During sea water desulphurization, water is the primary absorber. Adding suitable amounts of pH raising agent such as NaOH, lime solution (CaO) increases the effect or alters the process than the final pH of sulphur water. During oxidation reaction, oxidation reaction at low pH values (approximately around < 4.5) involving aeration the sulphite ion is oxidized to sulphate ion raising the pH to roughly around 5.6. Additionally aeration functions can eliminate CO2 from the water, thereby increasing pH during the neutralization reaction -
SO2 +H2O+1/2 O2 → S042- + 2H+
HC03- + H+ → CO2+H2O
Aeration is achieved by suitable aeration means such as air blowers or by creating water fountains/jets by means of pumps. Suitable source of oxygen supply include air. For neutralization achieved by dilution, fresh sea water is withdrawn from the sea with the help of dilution pumps. The above process further includes at least one cooling tower (205,305,405,505) operatively connected with at least one condenser (208,308,408,508) causing cooling of recirculating water.
In first embodiment of the present invention illustrated in figure 2, the makeup sea water is first used by the cooling tower (205) before being diverted to

the scrubber (201). Whereas in second, third and fourth embodiments of the present invention illustrated in figures 3-5 respectively, the makeup sea water is first used by the scrubber (301,401,501) before being recirculated within the apparatus (300,400,500). The latter being preferred over embodiment 1 as will be apparent by the following description.
Embodiment 1:
Figure 2 of appended drawings shows flow of the process using apparatus (200) in accordance with first embodiment of the present invention. In this process, makeup sea water is withdrawn by makeup water cooling intake pump (202), transported to cooling tower (205) via conduit (207) for cooling water make up, said cold water -generated therewithin entering condenser (208) via inlet (215) and exiting thereto via outlet (216) to reenter cooling tower (205) exiting thereto as blowdown water for disposal into the sea via conduit (212). Part of the water is lost through evaporation and drift loss (214). In this process, at least a part of blowdown water leaving conduit (212) is pumped through feed pump (217) into the scrubber (201) via inlet (206). the water used by the scrubber exits thereto via outlet (219) and enters the dilution chamber (210) in which said scrubber outlet water is diluted through makeup seawater pumped through dilution pump (209) entering the dilution chamber (210) via inlet (211). The scrubber outlet water contained within the dilution chamber (210) is aerated by suitable aeration means raising pH of the said scrubber outlet water rendering it suitable for disposing it into the sea via conduit (203). Addition of any alkali or pH raising substances is not necessary in this embodiment as additional sea water drawn from the sea through makeup water cooling intake pump (202) and aeration raise the pH of flue gas desulphurization cooling water.
Embodiment 2:
Figure 3 of appended drawings shows flow of the process using apparatus (300) in accordance with second embodiment of the present invention. Here the makeup sea water drawn by sea water intake pump (302) is first used by scrubber (301) for

contacting the flue gas comprising environmental contaminant present therein, said scrubber outlet water comprising absorbed environmental contaminant is neutralized by addition of suitable pH raising agent such as NaOH via inlet (309), the pH level of water above 6.5 for making it suitable for cooling tower make up. Addition of pH raising components eliminate the need for dilution process. This is followed by aeration by suitable aeration means (304) in aeration pond (306). The scrubber outlet water enters the settling pond (303) to effect settling of ash particles generated within the scrubber (301) thereafter entering the cooling tower (305) via conduit (307) for cooling water make up. The cold water generated during cooling in cooling tower (305) enters condenser (308) via inlet (315) and exits thereto via outlet (316) for re-entering cooling tower (305), said cooled water exiting cooling tower (305) as blowdown water to disposal to the sea via conduit (318). Part of the water is lost through evaporation and drift loss (314). The blow down from cooling tower is suitably treated before discharging to sea if required.
Embodiment 3:
Figure 4 of appended drawings shows flow of the process using apparatus (400), in accordance with embodiment 3 of the present invention. In this method the makeup sea water pumped by sea water intake pump (402) enters the scrubber (401) via inlet (407) and is first used by the scrubber (401). the used scrubber water exiting the scrubber (401) via outlet (407) is treated with pH raising agent such as NaOH via conduit (409) before entering the cooling tower (405) as Cooling Water make up. Here, cold water - generated during cooling in the cooling tower (405) enters the condenser (408) via inlet (415) and exits thereto via outlet (416) for re-entering the cooling tower (405), said cooled water exiting cooling tower (405) as blowdown water for disposal to the sea via conduit (418). Part of the water is lost through evaporation and drift loss (414). The blow down from cooling tower is suitably treated before discharging to sea if required. Due to ash settlement in cooling tower circuit unlike in other embodiment, this embodiment is more suited for oil fired stations prevalent in Middle East.

Embodiment 4:
Figure 5 of appended drawings shows flow of the process using apparatus (500) in accordance with embodiment 4 of the present invention. The makeup sea water is pumped through feed pump (517) via inlet (511) into the scrubber (501), contacts the flue gas contained therewithin followed by neutralization within the dilution chamber (510). the flue gas containing absorbed sulphur dioxide enters the dilution chamber (510) via inlet (519) for dilution with part of blowdown water received by conduit (506) and oxidation by suitable aeration means (504), said diluted water exits the dilution chamber (510) for disposal to sea by conduit (503). The cooling tower makeup sea water is pumped through intake pump (502) which enters the cooling tower (505) via inlet (507), as cooling water make up, the cold water generated therewithin enters the condenser (508) via inlet (515) and exiting thereof via outlet (516) re-entering cooling tower (505) for disposal to the sea via conduit (518). Part of the water is lost through evaporation and drift loss (514).
The methods of the present invention can be applied for a power plant of any capacity rating. Further the methods of the present invention can be used for part treatment of full treatment depending on the sulphur content or the coal quality. The amount of water withdrawn depends on the sulphur content in coal or oil. Nonetheless, the percentage of water consumed is substantially lesser than the conventional methods. As a comparative example, the aforementioned methods were applied to a typical 300MW for 50% of the flue gas treatment with sulfur content in coal of 0.6% power plant and amount of water used were as follows -
Table 1:

Amount of Amount of Total Sea water Amount
water used water used by amount of discharged of sea
by cooling flue gas sea water (D) water
tower as desulphurization withdrawn (cu.m/hr) used (E)
make up plant (B) (C) = (A) + = (B)-

water (A) (cu.m/hr) (cu.m/hr) (cu.m/hr) (D) (cu.m/hr)
Conventional method 4500 8000 12500 11850 650
Embodiment 1 5150 3200 8350 7700 650
Embodiment 2 (*) 4500 4500 3850 650
Embodiment 3 (*) 4500 4500 3850 650
Embodiment 4 4500 4500 9000 8350 650
(*) FGD Water used as Cooling water make up hence not included in column-A
As is apparent from the comparative results in Table 1, conventional flue gas desulphurization method requires high amounts of water (12500 cu.m/hr) to be withdrawn from the sea. Whereas in accordance with embodiments 1 and 4 of the present invention, wherein the withdrawn sea water is re-circulated partly, lesser amounts of water is withdrawn i.e. almost 66% (8350cu.m/hr) 72% (9000 cu.m/hr) of the water withdrawn in the conventional method of figure 1. Furthermore, in accordance with embodiments 2 and 3 of the present invention, in accordance with full re-crrculation, the sea water required to be withdrawn is still lesser i.e. almost 36% (4500 cu.m/hr) of the water withdrawn in the prior art process of figure 1. Therefore, it has been observed that for the same apparatus as compared to the prior art process, the amount of water withdrawn was observed to be convention method > Embodiments 1 and 4 of the present invention > Embodiments 2 and 3 of the present invention.
Therefore, the processes described in the present invention substantially reduced the amount of water withdrawn from the sea to almost to almost causes high amounts to water to be withdrawn from the sea. Due to reduced amount of water Tequired to be pumped, accordingly the electric power consumption incurred by pump which occupies the major portion of the total electric power consumption is substantially reduced, which is very economical.

The processes of present invention is ideal for use in existing power plants where installation of flue gas desulphurization plants in required as a retrofit as it involves minimum modification in the existing desulphurization plants thereby minimizing the investment costs and plant interruption. Specifically in embodiments 2 and 3 no additional dilution water pumps required as was seen in conventional methods.
While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any and all equivalents thereof.

Claims -
We claim;
1. A process for treating flue gas by using sea water which flue gas being
generated from burning of combustants and comprising at least one
environmental contaminant, in an apparatus (200,300,400,500) said process
comprising steps of -
(a) Contacting in a scrubber (201,301,401,501), said flue gas with sea water resulting in absorption of the environmental contaminant therewithin leading to acidification of the sea water;
(b) Transferring acidic sea water comprising absorbed environmental contaminant to a neutralization zone (230,330,430,530);
(c) Neutralizing, in the neutralization zone (230,330, 430, 530), said acidic sea water by at least one mechanism selected from addition of pH raising agent or aeration or dilution with makeup sea water thereby reacting said absorbed environmental contaminant with bicarbonate ions (HCO-3) present in used sea water to carbon dioxide and water rendering the blowdown water environmentally safe for returning to the sea
(d) Disposing at least apart of blowdown sea water into the sea
wherein at least a part of blowdown seawater is re-circulated between the scrubber and the neutralization zone (230, 330, 430, 530) eliminating the need to withdraw surplus amounts of sea water.
2. The process as claimed in claim 1 wherein the environmental contaminant
comprised in the flue gas is a combination of SOx, NOx, C02, particulate
matter and polycyclic aromatic hydrocarbon.

3. The process as claimed in any of the preceding claims wherein the environmental contaminant comprised in the flue gas is SOx, particularly SO2, and said process is flue gas desulphurization.
4. The process as claimed in any of the preceding claims wherein contacting flue gas comprising sulphur dioxide with makeup sea water causes formation of sulphite ions as -
S02 (Gas) → S02 (Liquid)
SO2 + H2O → HS03- + H+
HSO3- → SO32- +H+
5. The process as claimed in any of the preceding claims wherein during oxidation reaction, pH is raised by addition of suitable amounts of pH raising agents selected from alkali compounds such as NaOH and lime (CaO).
6. The process as claimed in any of the preceding claims wherein during neutralizing reaction, bicarbonate ions in sea water react with hydrogen to increase the pH.
HCO-3 + H+ → CO2 + H2O
7. The process as claimed in any of the preceding claims wherein oxidation
reaction at low pH values (approximately around < 4.5) involving aeration,
the sulphite ion oxidizes to sulphate ion raising the pH to roughly around
5.6 eliminating C02 from the water, thereby increasing pH during the
neutralization reaction -
S02 +H2O+I/2O2 → S042- + 2H+
HCO3- + H+ → CO2+H2O

8. The process as claimed in any of the preceding claims wherein the aeration is achieved by suitable aeration means such as blowers, creation of water fountains/jets by means of pumps.
9. The process as claimed in any of the preceding claims wherein air is used as oxygen supply source for converting sulphites in sea water to sulphates.
10. The process as claimed in any of the preceding claims wherein the dilution is achieved in a dilution chamber by receiving fresh sea water drawn from the sea with the help of dilution pumps.
11. The process as claimed in any of the preceding claims wherein the process includes at least one cooling tower (205,305,405,505) operatively connected with at least one condenser (208,308,408,508) causing cooling of recirculating water.
12. The process as claimed in any of the preceding claims wherein the makeup sea water is partly re-circulated within the apparatus (200,500).

13. The process as claimed in any of the preceding claims wherein the makeup sea water is fully re-circulated within the apparatus (300,400).
14. The process as claimed in any of the preceding claims wherein makeup sea water is first used by the scrubber (301,401,501) before being recirculated within the apparatus (300,400,500).
15. The process as claimed in claim 12 wherein the makeup sea water is withdrawn by cooling makeup water intake pump (202), transported to cooling tower (205) via conduit (207) for cooling water make up, said cold water generated therewithin entering condenser (208) via inlet (215) and exiting thereto via outlet (216) to reenter cooling tower (205) exiting thereto as blowdown water for disposal into the sea via conduit (212).

16. The process as claimed in claim 15 wherein at least a part of blowdown water leaving conduit (212) is pumped through feed pump (217) into the scrubber (201) via inlet (206).
17. The process as claimed in claim 16 wherein the water used by the scrubber exits thereto via outlet (219) and enters the dilution chamber (210) in which said scrubber outlet water is diluted through makeup seawater pumped through dilution pump (209) entering the dilution chamber (210) via inlet (211).
18. The process as claimed in claim 17 wherein the scrubber outlet water contained within the dilution chamber (210) is aerated by suitable aeration means raising pH of the said scrubber outlet water rendering it suitable for disposing it into the sea via conduit (203).
19. The process as claimed in claim 14 wherein the makeup sea water drawn by sea water intake pump (302) is first used by scrubber (301) for contacting the flue gas comprising environmental contaminant present therein, said scrubber outlet water comprising absorbed environmental contaminant is neutralized by addition of suitable pH raising agent such as NaOH via inlet (309), followed by aeration by suitable aeration means (304) in aeration pond (306).
20. The process as claimed in claim 19, wherein after aeration, the scrubber outlet water enters the settling pond (303) to effect settling of ash particles generated within the scrubber (301) thereafter entering the cooling tower (305) via conduit (307) for cooling water make up.
21. The process as claimed in claim 20 wherein cold water generated during cooling in cooling tower (305) enters condenser (308) via inlet (315) and exits thereto via outlet (316) for re-entering cooling tower (305), said

cooled water exiting cooling tower (305) as blowdown water to disposal to the sea via conduit (318).
22. The process as claimed in claim 14 wherein the makeup sea water pumped by sea water intake pump (402) enters the scrubber (401) via inlet (407) and is first used by the scrubber (401).
23. The process as claimed in claim 22, wherein the used scrubber water exiting the scrubber (401) via outlet (407) is treated with pH raising agent such as NaOH via conduit (409) before entering the cooling tower (405) as cooling water make up.
24. The process as claimed in claim 23, wherein cold water generated during cooling in the cooling tower (405) enters the condenser (408) via inlet (415) and exits thereto via outlet (416) for re-entering the cooling tower (405), said cooled water exiting cooling tower (405) as blowdown water for disposal to the sea via conduit (418).
25. The process as claimed in claim 14 wherein the makeup sea water is pumped through feed pump (517) via inlet (511) into the scrubber (501), contacts the flue gas contained therewithin followed by neutralization within the dilution chamber (510).
26. The process as claimed in claim 25 wherein the flue gas containing absorbed sulphur dioxide enters the dilution chamber (510) via inlet (519) for dilution with part of blowdown water received by conduit (506) and oxidation by suitable aeration means (504), said diluted water exits the dilution chamber (510) for disposal to sea by conduit (503).
27. The process as claimed in claim 26, wherein cooling tower makeup sea water is pumped through intake pump (502) which enters the cooling tower (505) via inlet (507) as cooling tower make up water, the cold water generated therewithin enters the condenser (508) via inlet (515) and exiting

thereof via outlet (516) re-entering cooling tower (505) for disposal to the sea via conduit (518).
28. The process as claimed in any of the preceding claims wherein the sea water disposed to the sea is substantially harmless to the aquatic environment of the sea.